That was the scale of this year's harvest that came into California Olive Ranch's milling plant near Willows (Glenn County), 2 1/2 hours north of San Francisco. The company is the largest producer of extra-virgin olive oil in the country, but was just one of the many producers in the state working overtime to turn the state's olives into high-quality oil.

It's indicative of the boom in California extra-virgin olive oil. This year's harvest of olives destined for oil was the largest ever, expected to produce more than 2 million gallons of high-quality oil. That's great news for consumers, who can expect more California extra-virgin olive oils on store shelves, with styles ranging from delicate to robust.

California produces less than 3 percent of the world's olive oil. But the local producers are setting the bar high, aiming for fresh oil that is often bottled on demand and quickly transported to markets.

The number of mills now numbers about 40, scattered throughout the state. More mills translate to higher quality, because the time between harvest and milling is a key factor in making extra-virgin olive oil.

Olive growers in other countries, such as Spain and Italy, tend to choose varieties of olives that have been traditionally cultivated for centuries. But California growers, unhampered by tradition, grow varieties that suit their microclimates and blend varieties that they think will produce interesting oil.

Blending varieties

The olives processed at the California Olive Ranch include Arbequina (70 percent of the plantings), Arbosana and Koroneiki, a Greek olive. Much of the oil is a blend, delicate and buttery, without much bitterness or pungency. But the ranch has a test plot of trees that are crosses of varieties that might eventually produce a more robust oil.

Trucks, each pulling two gondolas, transport the olives from the orchards to the mill. A hammer mill crushes the olives into a paste that is pumped into tanks and stirred slowly until the oil separates from the solids. Next the mass is centrifuged twice, which removes solid particles and water from the oil. As the oil spills from the last centrifuge into lines that pump it into storage tanks, it looks more like fruit juice than oil.

Deborah Rogers of the Olive Press in Sonoma runs an operation on a much smaller scale. Her single mill, chugging along at a half ton per hour, produces oil for her retail stores and for farmers' markets. She also mills oil for about 100 small producers who don't have mills of their own.

Quality is high

Her harvest wasn't as plentiful as 2010, but the fruit is sound and will make excellent oil. Olive varieties of every description pass through the mill, including two French varieties, Aglandau and Bouteillan, which are not often seen in California. Those oils will go into the Jaeger family's estate extra-virgin olive oil.

Rogers likes to use the Mission and Sevillano olives - some of the first olives planted in California - both for their taste and for their historical significance. She bottles them as single varieties, as well as Arbequina, Ascolano, Arbosana, Koroneiki and, when she has enough, Picual. Each has a special profile - Sevillano is delicate; Ascolano fruity with tropical notes; and Arbosana more robust.

The word about California extra-virgin oil is spreading - in September, Rogers represented the California olive growers and olive oil producers in Washington at the launch of the State Department's Diplomatic Culinary Partnership Initiative.

Four years ago, Thom Curry, co-owner of Temecula Olive Oil Co., purchased a mobile mill and started roving the state, setting up near orchards and milling olive oil. He calls his enterprise Olive to Bottle. His clients are small growers with modest amounts of fruit - many are wineries with a patch of olive trees. Curry described this year's harvest as, "Awesome. Delightful after last year. The quality is great and there are a lot more olives."

Ruth and Frank Mercurio opened their first We Olive store in 2003 in Paso Robles; last year, they opened their 11th store, in Thousand Oaks (Ventura County). Their focus is California extra-virgin olive oil that is certified by the California Olive Oil Council.

Certifying process

This certified oil is subject to chemical analysis and the scrutiny of a panel that blind-tastes the oil. If it passes muster - lab analysis in line, no defects detected by the panel, and a profile that includes some fruity characteristics - it qualifies as extra-virgin and the producer can put a seal on the bottle identifying it as such.

California olive oil has come a long way. The push to quality that began in the 1980s is coming to fruition, with many producers rivaling the best in the world.

Recipes, sources on G6

Olive oil styles

Here are various styles of oil, some California producers and some retail outlets. If you are interested in a specific oil, call ahead to check availability. Many oils, especially the olio nuovo - the new harvest - are made in limited quantities and can sell out quickly.

Olio nuovo

McEvoy, available at the McEvoy store in the Ferry Building and Bi-Rite Market in San Francisco.

Katz, available at Bi-Rite and the Pasta Shop, although it may be gone in the next few weeks.

Hillstone, available at Bi-Rite.

Delicate

California Olive Ranch for Everyday, available at the Pasta Shop in Berkeley and Oakland, Whole Foods and other grocers such as Mollie Stone's.

Corto, available at the same places as California Olive Ranch.

Calivirgin Arbequina, available at Rainbow Grocery in San Francisco and the Pasta Shop.

Medium

Pacific SunTehama County Blend, available at Rainbow Grocery and the Pasta Shop.

Bi-Rite Tuscan Style (Mendocino County), available at Bi-Rite.

We Olive Koroneiki, available in bulk at We Olive in San Francisco and Walnut Creek.

Robust

The Olive Press Italian Blend, available at the Olive Press stores in Sonoma and Napa.

Talcott Carneros Estate, available at We Olive in San Francisco and the Pasta Shop.

Confit Duck Legs in Extra-Virgin Olive Oil

Makes 6 confit duck legs

Confit meats are usually cooked at a low temperature in animal fat until they are tender, then stored in the same fat. This recipe uses a medium extra-virgin olive oil, producing a slightly lighter confit, with an olive oil flavor. Pacific Sun Tehama County has grassy and herbaceous green notes and tropical and buttery ripe flavors with medium bitterness and pungency. The salted and herbed legs sit for 24 hours before cooking, and then remain in the oil for 1 week before serving. Once the confit has been eaten, you can strain and cook with the slightly duck-tasting confit oil. A lentil salad goes nicely with the confit.

8 days in advance: Combine the salt, spices and pepper. Rub the duck legs with the mixture, dividing it evenly.

Put 3 of the legs in a glass or ceramic casserole dish, skin-side down. Distribute the garlic over the meat. Top with the remaining 3 legs, skin side up. Cover with plastic wrap and refrigerate for 24 hours.

1 week in advance: Choose a cooking vessel about 4 inches deep that will just contain the legs in two layers. Remove the legs from the casserole dish, rinse with cold water and place in the cooking vessel in two layers. To help estimate the amount of oil needed, add cold water to cover the legs. Remove the legs, then measure the remaining water; this will be the amount of oil you'll use. Dry the cooking vessel.

Pat the legs dry, then place them on a plate and let sit at room temperature for 1 hour.

Add the measured extra-virgin olive oil in to the cooking vessel and heat until the oil is warm to the touch, or about 100°. Put 3 legs into the oil, skin-side down. Place the remaining 3 legs on top, skin-side up. Add more oil, if needed, to fully submerge.

Attach a candy/deep frying thermometer to the side of the pot, and set over medium heat until the oil reaches 200°. Adjust the heat so the temperature of the oil hovers around 200°. Skim any foam that rises to the top. Cook until the meat starts to pull away from the drumstick bone and the juices run clear when poked with a skewer, about 1 1/2 to 2 hours, depending on the size of the legs. The meat should be tender, but still firm in texture. To test it, cut a small piece from one of the legs, let it cool somewhat and taste it.

Remove the legs to a clean glass or ceramic container. Using a fine mesh strainer, strain the oil over the meat to cover, leaving any solids or unclear juices behind. Cool to room temperature. Cover the container with plastic wrap and refrigerate for 1 week before serving. The legs will keep for at least 3 months, refrigerated.

To serve: Remove the legs from the oil and let them come to room temperature. Place a nonstick skillet that will hold the legs in one layer over medium heat. Add the legs to the skillet, skin-side down, and brown until crisp, about 3 minutes; add a little oil as needed. Turn the legs over and cook a few more minutes, until heated through.

Note: Medium extra-virgin olive oil brands include Pacific Sun Tehama County Blend, Bi-Rite Tuscan Style and We Olive Koroneiki. See the bottom of this page for retail availability.

Nutrition information: The calories and other nutrients absorbed from dry brines and marinades vary and are difficult to estimate. Therefore, this recipe contains no analysis.

Wine pairing: Match this with a Pinot Noir, Grenache or Cotes du Rhone.

Olio Nuovo Bruschetta With Persimmons & Prosciutto

Serves 4

This recipe celebrates the first oil from the mill, which is best used as drizzling oil. Although bitter and pungent, it is tamed when paired with food. Typical of this type of oil is McEvoy Ranch extra-virgin olio nuovo, an estate blend of Tuscan varieties, primarily Leccino. Its green olive flavors - fresh-cut grass, artichoke, hay, green tea - stand up to the bitterness and pungency.

Halibut Shallow-Poached in Extra-Virgin Olive Oil

Serves 4

A fruity, delicate oil with not much bitterness or pungency is a good choice for this recipe, complementing the taste of the fish without overpowering it. One choice is California Olive Ranch Everyday extra-virgin olive oil, a blend of Arbequina, Arbosana and Koroneiki olives that produces oil with ripe olive notes of butter, banana, flowers and sweet grass. Serve this over a bed of sauteed greens.

Instructions: Salt and pepper both sides of the fish; set aside. Choose a skillet or sloping-sided pan that just fits the fillets without crowding them.

Pour the oil into the pan, and heat over medium heat until the oil trembles and becomes aromatic. Slip the fillets into the pan. Regulate the heat so that the oil is at a simmer.

Cook until the fish becomes opaque halfway through its thickness, about 3 minutes. Turn the fish over and cook until it is opaque throughout, another 3 minutes or so. Test for doneness by poking a metal skewer into a piece, removing it then touching it to the back of your hand. If it feels lukewarm, cook a little longer.

Put the fish on warm plates, atop a bed of sauteed greens. Squeeze a few drops of lemon juice on the fish. Garnish with chives, if using.

Wine pairing: Select a white wine like an unoaked Chardonnay or Albarino, which complement seafood.

Extra-Virgin Olive Oil Chocolate Pound Cake

Makes 1 loaf, 8-10 servingsDelicate extra-virgin olive oil is a good choice for baking, but with chocolate, I prefer a robust oil with bitterness and pungency, such as the Italian Blend extra-virgin olive oil from The Olive Press. It has green olive flavors - grass, artichokes, green tea and spice - as well as nutty and buttery notes from ripe olives. This cake is delicious on its own, but can be dressed up with a dollop of whipped cream or Seville orange marmalade. If you want to accentuate the olive oil and chocolate flavors, lightly toast a piece of cake, then drizzle it with the same oil used to make it.

-- Extra-virgin olive oil for the pan

1 1/3 cups + 1 tablespoon unbleached all-purpose flour

1/2 teaspoon baking soda

1/4 teaspoon fine sea salt

1/2 cup unsweetened non-alkalized cocoa powder

4 large eggs, at room temperature

1 1/4 cups sugar

1/2 teaspoon pure vanilla extract

3/4 cup + 2 tablespoons robust extra-virgin olive oil (see Note)

Instructions: Move the oven rack to the middle of the oven and preheat the to 350°. Oil an 8 1/2- by 4 1/2-inch loaf pan.

Sift the flour, baking soda, salt and cocoa powder together, then sift a second time. Set aside.

In the bowl of a stand mixer fitted with the paddle attachment, beat the eggs on medium speed until they are homogenous. Add the sugar in a stream, increase the mixer speed to medium-high, and beat until the mixture increases in volume and becomes paler, about 2 minutes.

Reduce the speed to low. Add the vanilla extract. With the mixer running, add the dry ingredients in 3 additions, alternating with the olive oil in 2 additions, starting and ending with the dry ingredients and mixing just until incorporated. Stop and scrape the side of the bowl as needed.

Pour the batter into the prepared pan. Bake until a skewer inserted into the center comes out clean, about 45-55 minutes.

Cool the cake in the pan on a rack until it is cool enough to pick up the pan, about 15 minutes. Turn the cake out of the pan, then turn right side up and cool completely. The cake can be made a week or two ahead, wrapped well, and frozen. Bring to room temperature before serving.

Fran Gage is a San Francisco writer and expert olive oil taster. Her books include "The New American Olive Oil" and "Chocolate Obsession." E-mail: food@sfchronicle.com

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